✨ Feature: Add Caching System for Images and Pages

[dannycab]

Feature Request

Implement caching to avoid re-downloading same images and pages across runs.

Current Behavior

• Re-downloads images even if already present
• Re-fetches wiki pages even if unchanged
• Wastes bandwidth and time

Proposed Solution

from diskcache import Cache

class CachedHTTPClient:
    def __init__(self, cache_dir='.wikiaccess_cache'):
        self.cache = Cache(cache_dir)
    
    def get_page_raw(self, page_id: str):
        cache_key = f'page:{page_id}'
        if cache_key in self.cache:
            return self.cache[cache_key]
        
        content = self._fetch_from_wiki(page_id)
        self.cache.set(cache_key, content, expire=3600)
        return content

Features

• Cache with TTL (configurable expiration)
• Cache invalidation command
• Conditional requests (If-Modified-Since headers)
• Cache statistics
• Respect Cache-Control headers

Tasks

• Add diskcache or requests-cache dependency
• Implement page caching
• Implement image caching
• Add cache configuration options
• Add wikiaccess cache clear command
• Add wikiaccess cache stats command
• Add --no-cache flag for fresh fetches